[Synthesis]
General procedure for the synthesis of (S)-(+)-1-(2-pyrrolidinylmethyl)pyrrolidine from 1-[(2S)-2-pyrrolidinocarbonyl]-pyrrolidine: The reaction system was cooled down to 0 °C under nitrogen protection, and an anhydrous tetrahydrofuran (80 mL) solution of the amide (19.02 g, 113 mmol) was slowly added dropwise over a period of 3 hours to an anhydrous tetrahydrofuran (80 mL) suspension of lithium aluminum hydride (15.00 g, 396 mmol). 396 mmol) in anhydrous tetrahydrofuran (140 mL) suspension. After the dropwise addition, the reaction mixture was stirred at room temperature overnight, followed by heating and refluxing for 4 hours, and then continued stirring at room temperature overnight. Upon completion of the reaction, the reaction was quenched by slow dropwise addition of saturated aqueous sodium sulfate solution (20 mL). The crude reaction mixture was filtered through a diatomaceous earth pad and the filter cake was washed with ethyl acetate. The filtrates were combined and concentrated under reduced pressure to give a yellow oily crude product (14.54 g, 83% yield). Further purification by short distillation gave the colorless oily target product (S)-(+)-1-(2-pyrrolidinylmethyl)pyrrolidine (11.22 g, 64% yield). Specific optical rotation: [α]D20 +2.4 (c=2.4, EtOH). NMR hydrogen spectrum (CDCl3, 300 MHz) δ: 1.22-1.43 (1H, m, CH2), 1.68-1.81 (6H, m, 3×CH2), 1.82-1.95 (1H, m, CH2), 2.31-2.37 (1H, dd, J=5.2, 11.9 Hz, CH2), 2.45-2.61 (6H , m, 3 × CH2, NH), 2.81-2.89 (1H, m, CH2), 2.94-3.02 (1H, m, CH2), 3.17-3.26 (1H, m, CH). NMR carbon spectrum (CDCl3, 75.5 MHz) δ: 23.4 (2×CH2), 25.0, 30.1, 46.1 (3×CH2), 54.6 (2×CH2), 57.4 (CH), 62.1 (CH2). Mass spectrum (ES+) m/z: 155 [(M+H)+, 100%]. |
[References]
[1] Journal of the American Chemical Society, 1987, vol. 109, p. 2040
[2] Bulletin of the Chemical Society of Japan, 1990, vol. 63, # 3, p. 721 - 727
[3] Patent: US2003/195190, 2003, A1
[4] Patent: US4550107, 1985, A
[5] Organic Letters, 2009, vol. 11, # 15, p. 3270 - 3273 |